Contents

Introduction

The Raspberry pi mother board has one major problem with i2s audio interface. The clocks coming from CPU can only output one frequency clock perfect, resulting in major problems with audio files sampled at 44khz and multiple. Too much jitter on i2s clocks. So we enter the master mode for i2s. Instead of the RPI giving the clock on the line, the DAC itself sends the clocks and RPI sends the data (file tobe played). Since we used 2 clocks the problem above solved.

RPI-HIFI-DAC is unique, because of the way we have implemented the design. First we separated the power on 3 channels and filter it: one for the digital side, the second for analog and third for the clocks themselves. We use some of the good brand LDOs on the market. In addition, we used two oscillators with very low jitter for clock units. Finally, on the analog stage we are using a film capacitor (not ceramic) for a quiet DC to feed the TI IC to reduce signal distortion.